The two-ply nonwoven fabric laminates of the present invention are lightweight fabric laminates which are relatively high in both air porosity and liquid strikethrough resistance. This combination of high liquid strikethrough resistance and high air porosity can be obtained in nonwoven fabric laminates of the present invention having substantially lower basis weight than other nonwoven fabric laminates having comparable air porosity and liquid strikethrough resistance properties.
The nonwoven fabric laminates of the present invention have many applications and, in fact, may be used wherever their liquid strikethrough resistance/air porosity/basis weight relationships would be advantageous. For example, the nonwoven fabric laminates could be used in the manufacture of clothing where a barrier to liquid strikethrough is desired, e.g. laboratory costs, artists' smocks, hospital scrub clothes, or the like.
The primary use envisioned for the two-ply nonwoven fabric laminates of the present invention is for disposable surgical gowns and drapes. The laminates are especially suitable for surgical gowns are high liquid strikethrough resistance, is needed to prevent liquid-borne contaminates from passing through the gown fabric, but where fabric light in weight and having high air porosity is important for the comfort of the wearer. The two-ply nonwoven fabric laminates of the present invention are particularly suitable for use in the manufacture of disposable zoned surgical gowns. Such gowns have zones of extra water repellency or water impermeability in areas where contact with contaminated fluids is most likely to occur, especially the upper gown front and the lower sleeves of the gown.
Prior art workers have developed a number of fabrics for use in surgical gowns, surgical drapes and the like. There are a number of critical physical properties which are sought for such fabrics. These properties include: essentially no particulate discharge (lint or the like), essentially no abrasion or pilling, high liquid strikethrough resistance, high air porosity, adequate strength and tear resistance, lightweight, and cloth-like aesthetic properties. Prior art workers have found that it is necessary to aim for the best possible tradeoff among at least some of these properties because they tend to work against each other. A good example of this is air porosity on the one hand and liquid strikethrough resistance on the other. Another example is the weight of the fabric laminate and strength and tear resistance.
In producing fabric laminates for disposable products, it is necessary to strive for the least expensive laminates which provide the properties listed above, so that such products can be affordable. No single nonwoven material has been discovered which alone can provide all the desired properties listed above. Therefore, laminates of two or more materials have been combined in order to achieve a better balance of such properties. For economic reasons, it is generally desirable to have the fewest plies of material possible, while retaining the desired properties of such laminates, in order to minimize both the material and processing costs. For such economic reasons, a two-ply nonwoven fabric laminate having the above properties is highly desirable.
Exemplary prior art references which disclose two-ply nonwoven fabric laminates are disclosed in the following U.S. Pat. Nos. 3,327,708 issued to Sokolowski on June 27, 1967; 3,615,976 issued to Endres & Lewis on Oct. 26, 1971; 3,674,594 issued to Persson on July 4, 1972; 3,695,985 issued to Brock & Thomas on Oct. 3, 1972; 3,753,844 issued to Braun on Aug. 21, 1973; 3,788,936 issued to Brock, Hansen & Wilson on Jan. 29, 1974; 3,793,133 issued to Beaudoin, Brock & Minshell on Feb. 19, 1974; 3,870,592 issued to Brock & Hudson on Mar. 11, 1975; 3,900,632 issued to Robinson on Aug. 19, 1975; 3,770,562 issued to Newman on Nov. 6, 1973; and 3,809,077 issued to Hansen on May 7, 1974. Other U.S. patents which disclose disposable nonwoven fabric laminates include U.S. Pat. Nos. 3,072,511 issued to Harwood on Jan. 8, 1963; 3,600,262 issued to Frank on Aug. 17, 1971; 3,629,047 issued to Davison on Dec. 21, 1971; 3,862,877 issued to Camden on Jan. 29, 1975; 4,113,911 issued to LaFitte & Camden on Sept. 12, 1978; 4,142,017 issued to Blackburn & Goodwin on Feb. 27, 1979; and 4,196,245 issued to Kitson, Gilbert & Israel on Apr. 1, 1980. Many of the aforementioned patents also disclose processes for producing nonwoven fabric laminates; such a process is also disclosed in U.S. Pat. No. 2,954,817 issued to Havemann on Oct. 4, 1960.